When an vehicle collides with other vehicle or a structure, etc., the driver might suffer a secondary collision with a steering wheel by its inertia. The vehicles manufactured over the recent years broadly employ an impact absorbing type steering column apparatus, together with a safety belt and an air bag, for the purpose of preventing the driver from being injured in that case. There are now various types of impact absorbing mechanisms to be employed in an impact absorbing type steering column apparatus. However, ones of a double tube scheme which get collapsed simultaneously with a steering shaft when the driver suffers a secondary collision so as to absorb the impact energy thereof on that occasion are generally employed.
In an impact absorbing type steering column apparatus of this scheme, at a secondary collision of the vehicle, when an upper column on the vehicle-rear-side moves to the front side of the vehicle with respect to a lower column which is fixed to the body of the vehicle, the upper column moves to the front side of the vehicle while resisting a frictional force (sliding resistance) which is caused by a sliding contact with the lower column.
However, when this upper column moves (slides) to the front side of the vehicle, the tip end edge thereof might be twisted with respect to a sliding surface of the lower column, so that the upper column can not always slide smoothly.
For these reasons, it is disclosed in Japanese Patent Application Laid-Open No. 8-142877 that a cylindrical spacer formed of synthetic resin is press-fitted into between the lower column and the upper column, whereby the tip end edge of the upper column smoothly slides on the outer peripheral surface of the cylindrical space. With this arrangement, “the twist” of the lower column can be prevented.
In Japanese Patent Application Laid-Open No. 2002-302048, disclosed is a thin film-like friction reducing material which is formed of polymer material and coats one of the sliding surfaces of the two columns in the thickness of 10 to 100 μm, whereby the frictional resistance between the sliding surfaces of the two columns are reduced, so as to prevent “the twist” of the upper column.
However, when the cylindrical space is formed of synthetic resin and the hardness of one of the columns which serves as the outer column is low, as disclosed in Japanese Patent Application Laid-Open No. 8-142877, both the columns might be deformed and difficult to slide or scoring or the like might be caused by deformation.
Also, even when one of the sliding surfaces of the outer and inner columns is coated with a thin film-like friction reducing material formed of polymer material, as disclosed in Japanese Patent Application Laid-Open No. 2002-302048, if the hardness of the outer column or the inner column is low, the column might not be smoothly collapsed.
Note that when an end of the spacer might be provided with a flange, this flange might be caught and might not be collapsed smoothly at a secondary collision. The same might happen even if the spacer had been divided.